Field of the Present Invention
The present invention relates generally to an alarm unit for providing an audible signal when a fire extinguisher is removed from its storage post and, more particularly, to such an alarm unit which can be conveniently carried by the fire extinguisher so as to be portable therewith or which can be conveniently secured to the stationary storage post for the fire extinguisher.
Description of the Prior Art
Fire extinguishers are often stored in highly visible and readily accessible storage areas in a plurality of locations throughout large public and private buildings as is often required by fire regulations and ordinances. However, such positioning makes the fire extinguishers vulnerable to tampering by pranksters, vandals and the like. Accordingly, it would be advantageous to be able to detect such tampering by providing an alarm which detects when the fire extinguisher is being dislocated or removed from its storage station or post.
One previously known device for sounding an audible alarm when the storage post is tampered with is shown in U.S. Pat. No. 4,015,250 to Fudge. Fudge discloses a cabinet in which the fire extinguisher can be stored. The cabinet includes a hinged door and a plunger-type switch which is activated when the door is opened and, thus, sounds a local alarm secured within the cabinet. Nevertheless, the fire extinguisher can be removed from the cabinet and silently transported away once the fire extinguisher has been removed from the area in which the local alarm is sounded. Moreover, the alarm can be easily deactivated by pressing in the plunger or closing the cabinet door once the fire extinguisher has been removed. Thus, the alarm may be audible for only a short interval which is insufficient to provide adequate warning of tampering with the fire extinguisher.
Another known alarm for detecting removal of a fire extinguisher from its storage post is disclosed in U.S. Pat. No. 4,003,048 to Weise. Weise discloses the use of an electrically conductive breakaway lanyard which is looped around the neck of a fire extinguisher. The ends of the wire lanyard are locked in a spaced apart parallel disposition by and extend outwardly from a guide block. Thus, the ends of the lanyard are positioned to be slidably insertable into female receptacles in a housing jack secured to a wall mounting bracket. The receptacles include conductive elements which permit the lanyard to complete the supervisory electrical circuit. When the lanyard is broken or the prongs removed from the receptacles, the supervisory circuit is open circuited whereby a relay in a second alarm circuit closes and causes the alarm to provide a warning signal. Such an alarm system is disadvantageous for the reason that electrical power must be continuously applied to the supervisory circuit. Moreover, the lanyard could easily be shortcircuited before the lanyard portion surrounding the neck is broken so that the extinguisher can be removed without causing the alarm to sound. In addition, Weise teaches that the alarm signal is remote from the fire extinguisher itself and even from the stationary storage post.
Another previously known type of alarm comprises the use of a trip wire which is biased at a predetermined tension so that increasing or decreasing the tension of the wire actuates an alarm signal. However, these devices are disadvantageous for the reason that they are quite complicated and thus expensive to produce. Moreover, although such devices are quite sensitive and, therefore, are difficult to override, they require concerted effort to accurately adjust the trip wire to its operative position.